Vibratory energy method and apparatus



Oct. 5, 1965 c. A. BOYD ETAL 3,209,572

VIBRATORY ENERGY METHOD AND APPARATUS Filed June 21, 1963 4 Sheets-Sheet 1 F/GZ INVENTO/PS. CHARLES A. BOYD NICHOLAS MAROP/S B JAMES BYRON JONES ATTORNEY Oct. 5, 1 965 c.'A. BOYD ETAL 3,209,572

VIBRATORY ENERGY METHOD AND APPARATUS Filed June 21 1963 4 Sheets-Sheet 2 INVENTORS CHARLLS' AQBOVD NICHOLAS MAkOfi/s BY JA -.5 area/v JONES ATTORNEY Oct. 5, 1965 c. A. BOYD ETAL 3,209,572

VIBRATORY ENERGY METHOD AND APPARATUS I Filed June 21, 1963 4 Sheets-Sheet :5

INVENTORS CHARL ES ,4. 50m N/CHOLAS MA/POP/S BY JAMES BYRON JONES A7 7' OfP/VE V Oct. 5, 1965 c. A. BOYD ETAL VIBRATORY ENERGY METHOD AND APPARATUS 4 Sheets-Sheet 4 Filed June 21, 1963 (.1 A/O/SWJJ a/wmraa V w J E m m m w A Mm a R r m sr [M A cmm United States Patent 3 209,572 VIBRATORY ENERGYMETHOD AND APPARATUS Charles A. Boyd, James Byron Jones, and Nicholas Maropis, West Chester, Pa., assignors to Aeroprojects Incorporated, West Chester, Pa., a corporation of Pennsylvania Filed June 21, 1963, Ser. No. 289,559 13 Claims. (Cl. 72-277) This invention relates to a method and an apparatus employing vibratory energy, and more particularly to a method and apparatus for drawing articles including wire through a die.

Drawing is a well-known manufacturing process for forming materials, and it can be performed wet or dry, single stage or multi-stage, and with or without applying heat to the material before it is drawn through a die. In some materials, hardness may be increased by the drawing operation so that annealing is required before further drawing. Drawing stresses the material above its elastic limit to permit plastic flow.

It has been proposed heretofore to employ vibratory energy when drawing material, as in United States Patents 2,393,131; 2,568,303; and 2,638,207 which have not been commercialized, apparently because of significant deficiencies with respect to the application and utilization of the vibratory energy there described. Therefore, it is a principal object of the present invention to provide a practical, as well as more effective, method and apparatus for drawing materials.

In addition to the advantages obtained by use of the herein described apparatus, improved results are obtained when (in connection with an appreciable portion of the length of the material such as wire, to be drawn) the drawing process is started under conditions of application of a relatively low level of vibratory energy. In connection with drawing the remaining portion of the material through the die, the power level is gradually increased to enable a desired production level for obtaining an acceptable drawn product.

Under certain circumstances, the initial threading of the die preparatory to drawing with a lead-in section length of the material is also accomplished under vibratory activation but at a relatively low power level.

It has been found that a greater area reduction of a given material per pass through a die is obtainable by means of the present invention, or there is a reduced drawing tension and/or an increased drawing speed (as when utilizing the present invention to obtain a conventional area reduction but under improved conditions). Moreover, there is a minimizing or elimination of the breakage of the material normally encountered when applying production levels of vibratory power immediately upon initiation of drawing and/ or on threading of draw dies preparatory to drawing. Material breakage is, of course, highly undesirable in a production operation, being wasteful of both material and operator time.

Particular advantages accrue when there is suitable programming of the stages of application of various amounts of vibratory power, drawing tension, and/or drawing speed. Thus, for a given material and a given desired reduction in cross section or diameter of that ma terial, for example, programmed control of ultrasonic power application is provided in relation to drawing speed and/or drawing tension during the buildup period pre paratory to ultimately desired operating speed. Espe- "ice cially, advantages obtain when the drawing speed is maintained at a rate in relationship to a given drawing tension limit and to a given acoustic power limit, such drawing rate being within the boundaries of the two limits of drawing tension and acoustical power.

Additional aspects of the present invention are that dies are easy to change, that the electrical equipment can be located remote from the die and lubricant applicator, and that maintenance and set-up of the equipment are simplified.

It is an object of the present invention to provide a novel apparatus and method for drawing wire.

It is another object of the present invention to provide an efficient apparatus and method for increasing the amount or reduction of a given material per pass through a die while drawing wire.

It is another object of the present invention to provide an efficient apparatus and method for decreasing the pulling force necessary to draw wire.

It is another object of the present invention to provide a novel apparatus and method which facilitates drawing wire difficult or impossible to draw heretofore.

It is a further object of the present'invention to provide a novel apparatus and method for increasing the drawing speed at which materials can be drawn in the form of Wire.

It is still another object of the present invention to provide a novel apparatus and method which facilitates the efficient multi-stage drawing of material in the form of wire.

It is still another object of the present invention to provide a method of drawing wire which substantially reduces the tendency to breakage of the material.

Other objects will appear hereinafter.

For the purpose of illustrating the invention there is shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is a front elevation view of a wire drawing apparatus.

FIGURE 2 is a diagrammatic enlarged view of the elements illustrated in FIGURE 1, with portions broken away for purposes of clarity.

FIGURE 3 is a perspective view of another embodiment of the present invention.

FIGURE 4 is a sectional view taken along the lines 4-4 in FIGURE 3.

FIGURE 5 is a view showing the details of a portion of another embodiment for activating and supporting the die.

FIGURE 6 is a graph generally illustrating the relationships between drawing tension and drawing speed at various acoustic power levels.

Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIGURES l and 2 a wire drawing apparatus designated generally as 10.

The apparatus 10 is in the nature of a drawing machine and includes a housing 12. Supported by the housing 12 and at opposite ends thereof, there is shown an unwind spool 14 and a windup spool 16, each mounted for rotation about its longitudinal axis. Adjacent spool 14, there is provided means for lubricating the wire 48 being unwound from spool 14. Such means may be an absorbent pad 18 (over which the wire 48 is caused to pass) and a nozzle 20 for dispensing (as by dripping) lubricant onto the wire 48 and pad 18. Adjacent the lubricating means 3 18-20, there is shown an idler spool 22, below which the Wire 48 is caused to pass.

Intermediate idler spool 22 and windup spool 16 is a vibratory transducer-coupling system generally designated as 11. Transducer-coupling system 11 comprises a transducer 42, acoustic coupler 26, and die 24, with transducer 42 and coupler 26 being advantageously positioned to one side of the axis of die 24 so as to permit non-interference with the passage of wire 48 to spool 16.

The transducer 42 may be of the magnetostrictive type and of conventional construction comprising a onehalf-wavelength-long core of nickel, nickel-iron alloy, Permendur (an iron-cobalt alloy), Alfenol (an aluminum-iron alloy), or other magnetostrictive material, properly dimensioned to insure axial resonance with the frequency of alternating current applied thereto by coil 44 so as to cause it to increase or decrease in length according to its coefficient of magnetostriction. The detailed construction of a suitable magnetostrictive transducer is well known to those skilled in the art and does not form a part of the present invention and, accordingly, no description of its construction will be made herein. It will be appreciated by those skilled in the art that in place of the magnetostrictive transducer 42 shown in the drawing, other known types of transducers may be substituted; for example, electrostrictive or piezoelectric transducers made of barium titanate, quartz crystals, lead titanate-lead zirconate, etc., may be utilized. Coil 44 is connected to a power supply (not shown) incorporating an oscillator and amplifier suitable for powering the transducer 42; such equipment is well known to the art. Other types of power sources, such as a motor alternator with frequency control provision, can also be used for driving or powering coil 44 and transducer 42. The transducer 42 is also provided with a polarizing coil 46, the desirability of magnetically polarizing the transducer 42 by means of polarizing coil 46, in order for the metal laminations in transducer 42 to efiiciently convert the applied energy from excitation coil 44 into elastic vibratory energy, being readily understood by those skilled in the art.

Transducer 42 is fixedly joined to one end of acoustic coupler 26, preferably by brazing or some other type of metallurgical joint. Acoustic coupler 26 is essentially an acoustic transmission line, there being a wide variety of forms of such transmission lines known to the art. As shown in FIGURES 1 and 2, coupler 26 is also a mechanical transformer of a general type well known to the art, being at least partially of contoured (such as tapered) construction for purposes of increasing amplitude of vibration. Coupler 26 may comprise a single member or, as shown here, for manufacturing convenience, it may comprise two pieces (which are here shown to be screw-connected by means of a stud), one or both of which may be tapered.

If of tapered construction, the tapered portion of coupler 26 may be shaped so as to have a taper that is, for example, an exponential function of its length and that satisfies the following equation:

S S c where S is the reduced area at any section of the tapered portion, S is the area of the untapered portion (nearest the transducer), T is a constant describing the taper, and 1 is the length of the tapered coupler. This equation and the boundary conditions for resonance of a coupler such as coupler 26 are set forth at page 163 of Piezoelectric Crystals and Ultrasonics by Warren P. Mason, published in 1950 by D. Van Nostrand Company.

Coupler 26 will have its larger end portion fixedly joined to transducer 26, as aforesaid, and its smaller end joined to the die 24, inasmuch as the tapered portion by means of its increasingly smaller cross section affords the increased amplitude of vibration which will be utilized by the die 24.

As shown in FIGURES 1 and 2, the taper of coupler 26 begins shortly after the junction of coupler 26 with transducer 42 and proceeds to a region near the die area, at which region the taper ceases and the remainder of coupler 26, namely, the region near the die area, is in the form of a cylindrical rod. Such an arrangement of taper and rod is a construction well within the skill of those skilled in the art. Likewise well within such skill is the multiple one-half wavelength dimensioning (for operation at a resonant frequency) of the combination of coupler 26 and die 24, in connection with materials suitable for acoustic purposes, which are preferably low hysteresis metals and alloys such as steel, nickel, aluminum-bronze, beryllium-copper, or Monel.

Die 24 has an orifice defining a passageway through which to draw wire in order to reduce the wire diameter, and coupler 26 has a bore 28 extending through a portion thereof and in line with the orifice in die 24.

Preferably, for support purposes and to minimize frequency shift of the vibratory apparatus and loss of vibratory energy to the associated supporting members for the transducer-coupling system 11, the system 11 will be supported by one or more force-insensitive mounts. In the illustrated embodiment of FIGURES 1 and 2, two such mounts are included, one mount being generally designated as 15 and the other as 17.

Mount 15 comprises a sleeve 30, one-half wavelength long at the operating frequency and made from steel or other low hysteresis material such as nickel, aluminumbronze, beryllium-copper, or Monel. Sleeve 30 surrounds and is concentric with the coupler 26. One end 32 of the sleeve 30 is metallurgically bonded to the coupler 26 preferably at an antinode or loop region of the vibration on the latter, and the other end 34 of the sleeve 30 is free from attachment. Sleeve 30 is provided with a radially outwardly extending flange 36 located one-quarter wavelength from the free end 34, and a true node will develop at flange 36. Reference is made to United States Patent Nos. 2,891,178; 2,891,179; and 2,891,180, each of which issued in the name of William C. Elmore and is entitled Support for Vibratory Devices. Flange 36 is adapted to be secured to a frame support 38 by means of a ring 40.

Mount 17 comprises a sleeve 54, which is provided with a radially outwardly directed flange 58 and is otherwise dimensioned in the same manner as sleeve 30 to provide a force-insensitive mount for the die 24. Sleeve 54 is threadedly connected to threads 56 on coupler 26 preferably at a loop area of the vibration on the latter. Flange 58 is adapted to be secured to a frame support bracket 59.

Wire 48 which is to be drawn is wound on spool 14. The lead-in section end of wire 48, in accordance with standard practice, may be provided with a reduced diameter portion 50, which may be accomplished in a variety of ways including swaging. Such portion 50' is fed through the die 24 and the bore 28, and then secured to spool 16, the portion of the wire 48 adjacent to and ahead of die 24 preferably being covered with a lubricant.

Thereafter, manipulation of the dials and other switches on the housing 12 will facilitate activation of transducer 42 and mechanical winding of spool 16 to pull the wire 48 through the orifice of die 24. Vibratory energy is transmitted from the transducer 42 by way of coupler 26 to the die 24, which is thereby activated axially or longitudinally of the wire passing through the die.

Transducer-coupling system 11 may be vibrated at a frequency in the audible range (up to about 15,000 cycles per second) or in the ultrasonic range (generally above about 15,000 cycles per second). A preferred frequency would be in the range of from about 3,000 to about 50,000 cycles per second, with the optimum being 5 between about 14,000 to about 35,000 cycles per second. Dies (plus die-retaining elements) of sufficient size and mass as to give a mass loading effect on a transducercoupling system having a given resonant frequency should be used with a unit having a relatively lower resonant frequency, or system acoustical length adjustment made.

The apparatus facilitates a single draw of the wire 48. In FIGURES 3-5, there is illustrated an embodiment of the present invention, designated generally as 60, which facilitates multi-stage drawing of wire, for purposes of progressively increased reduction.

The apparatus 60 includes a housing (not shown), comparable to housing 12 (of FIGURES 1 and 2). Supported by the housing and at opposite ends thereof, there is shown an unwind spool 62 and a windup spool 64, each mounted for rotation about its longitudinal axis. Between the spools 62 and 64 are a pair of capstan spools 66 and 68, each rotatably supported for rotation about its longitudinal axis. Each of the capstans 66 and 68 is provided with a plurality of grooves of progressively smaller diameter for accommodating the wire 70. A lubricating apparatus and lubricant may be provided to apply lubricant to the wire 70, as for example, before it enters each of the dies.

Intermediate capstans 66 and 68 are a plurality of transducer-coupling systems generally designated as 61, each of which is slightly staggered in its arrangement with respect to the adjacent system to provide clearance. Each transducer-coupling system comprises three transducers (108, 110, 112), an acoustic coupler 90, another acoustic coupler 84, and a die 76. Since each transducer-coupling system is the same, except for the diameter of the orifice of the respective die associated therewith, only one transducer-coupling system will be described in detail.

Each of transducers 108, 110, and 112 is provided with an excitation coil (not shown), and the description given hereinbefore as to transducer 42 is applicable to each of magnetostrictive transducers 108, 110, and 112, including the fact that other types of transducers may be substituted for such transducers.

Acoustical coupler 90 is essentially a mechanical transformer and is of contoured construction for purposes including the increasing of the amplitude of vibration. Reference is made to United States patent application Serial No. 114,932 filed June 5, 1961, in the names of James Byron Jones et al., entitled Tree Limb Vibratory Device, for details concerning construction of a coupler such as coupler 90 (with its associated transducers as aforesaid) is particularly suitable for application of relatively high levels of vibratory energy at a given frequency, and for avoiding undesirable modes of vibration in connection with both the powering and the operation of a relatively large single coupler-transducer arrangement, as well as for appropriate access and attachment to a member such as coupler 84 in order to vibrate it and the die axially of the direction of passage of the wire.

The end of coupler 90 remote from the transducers is fixedly secured, as by a metallurgical joint such as a brazed joint, to one end of the acoustical coupler 84. Coupler 84 is essentially an acoustic transmission line and as shown in FIGURE 3 is also a mechanical transformer, being at least partly of contoured (such as tapered) construction for purposes of increasing the amplitude of vibration. In this embodiment, coupler 84 is in the form of a cylindrical rod from its junction with coupler 90 until near its other end, which other end is tapered in ac cordance with the taper equation included hereinabove, as shown more clearly in FIGURE 4. For purposes of manufacturing convenience, coupler 84 may be made in two pieces (one piece being the cylindrical portion, for example, and the other being the tapered portion) which are made individually and then metallurgically joined together, although coupler 84 can be fabricated as one piece.

The end of coupler 84 is counterbored to receive a major portion of die 76, and the die 76 is secured between the die clamp assembly 78 and the end of tapered coupler 84 by means of cooperative threads on said coupler and said die clamp assembly.

Die 76 has an orifice defining a passageway through which to draw wire in order to reduce the wire diameter, and coupler 84 is provided with a bore 86 entering through a portion thereof and in line with the orifice in die 76. The bore is, as shown, enlarged within the tapered portion of coupler 84.

The transducer-coupling system above described is constructed in accordance with the well known multiple onehalf wavelength dimensioning (for operation at a resonant frequency) well known to the acoustics art, with the result that die 76 is positioned at an antinode or loop of the vibration of the system for the most advantageous use of such vibration to aid the drawing operation.

Preferably, for support purposes and to minimize frequency shift of the vibratory apparatus and loss of vibratory energy to the associated supporting members for the transducer-coupling system, the system is supported by one or more force-insensitive mounts. In the illustrated embodiment of FIGURES 3 and 4, two locations for such mounts are shown, one being on coupler 90 and the other on coupler 84. I

The description given hereinabove as to construction and operation of mount 15 (of FIGURES 1 and 2) is generally applicable to the mount 98 on coupler 90, except that, instead of being a cylindrical sleeve such as sleeve 30, mount 98 comprises a pair of fiat plates, one attached to each of the two sides of coupler 90.

The description given hereinabove as to construction and operation of mount 15 (of FIGURES 1 and 2) is generally applicable to the mount 72 on coupler 84, except that, instead of being a cylindrical sleeve such as sleeve 30, mount 72 comprises a single curved plate which is removably secured as by bolt connection to the support bracket 74, and connection arrangement corresponding to the flange '77 in FIGURE 5, and the bolt 80 of FIGURE 4 is comparable to the stud 99 of FIGURE 3 which is used as is the bolt 80 to attach the mount 98 to supporting structure for the systems 61.

While three transducer-coupling systems, each incorporating a die, are shown in FIGURE 3, it will be appreciated that a greater or lesser number may be utilized as desired. It is to be noted that a separate transducercoupler arrangement is used for each die, this having been found to be preferable to an arrangement having the same source of vibratory energy (such as a common transducer) for reasons of controlling power to individual strands. It is also to be noted that each of the dies is preferably removably secured to the adjoining acoustical coupler, so that a given die may be replaced.

The operation of the multi-draw apparatus 60 is as follows: Spool 62 stores the undrawn wire and feeds the wire pulled from it through the first die by the powered capstan 68. The wire then returns to powered capstan 66 and proceeds through the second die and thence back to the second groove on capstan 68, from which the wire returns to capstan 66 and thence through the third die and back to the largest diameter groove on capstan 66, from which it issues to the powered take-up spool 64. The grooves on capstans 66 and 68 progressively increase in diameter from the groove first contacted by the undrawn large-diameter wire from pay-01f spool 62. Increases in diameter of the various grooves on capstans 66 and 68 correspond to the increasing speed of the wire which results from its becoming smaller in diameter as it is drawn. Thus, take-up spool 64 will rotate faster than pay-off spool 62 in inverse proportion to the total reduction in wire cross section as it passes through the various dies. Similarly, each groove of capstans 66 and 68 progressively increases its diameter from the wire input side to the wire output side.

about feet is generally suitable.

In FIGURES 1 through 4, the coupler which is secured to the die is shown to be elongated and bent, an arrangement which is advantageous for mounting the requisite couplers and transducers in a position where they may be easily maintained and disposed remote from the dies and rotating spools. Such elongated couplers have a maximum cross-sectional dimension which is preferably less than one-quarter wavelength in the material of which they are made at the frequency of operation. They can be of substantial length with no immediately evident limits, although, due to hysteresis losses in materials, their length should probably be less than around to feet for efficient operation, and in configurations such as those of FIGURES 1 through 4, a length of up to The bendability or formability of the material of such acoustical couplers enables them to be bent so as to circumvent obstructions. For efficient power transmission along such couplers, the bend radius and other limitations are set forth in detail in co-perrding patent application Serial No. 120,233 filed June 28, 1961, by Dennison Brancroft et al., entitled Apparatus and Method for Introducing High Levels of Vibratory Energy to a Work Area.

While the embodiment of FIGURES 3 and 4 is presently preferred, it will be appreciated that many variations thereof are possible within the skill of the art besides those of FIGURES 1 and 2. Thus, in FIGURE 5, for example, there is shown another construction and arrangement for die 76, coupler 84, and the associated support mount 72, these parts in FIGURE 5 being designated 71, 79, and 73, respectively.

Thus, in FIGURE 5, the construction and arrangement resembles that of FIGURES 1 and 2, rather than that of FIGURES 3 and 4. The coupler 79 in its approach to the die does not have a tapered configuration but is in the form of a cylindrical rod. The amount 73 is secured by means of cooperating threads to a portion of coupler 79 nearest the die. Also, the die 71 is secured to the mount 73 by means of cooperating threads, such as internal threads on cap 75 and external threads on mount 73. The flange 77 on mount 73 (corresponding to the flange 58 on sleeve 54) is adapted to be secured to a frame support 81 (corresponding to frame support 59).

The configuration of FIGURE 4 is preferable to the configuration of FIGURE 5, in view of having the support mount attached to a coupler portion having a lesser amplitude of vibration, thereby subjecting the support mount to a lesser degree of stress with resultant improved vibrational operation of the support mount.

It is to be noted that the apparatus described herein is preferably arranged to be isolation-mounted so as to avoid undesirable transfer of acoustic energy from the transducer-coupling system to the drawing machine per se and/ or from the machine (because of inherent resonances therein) and the work and/ or transducer-coupling system.

Referring now to FIGURE 6, there is shown a diagram generally illustrating the relationship between drawing tension and drawing speed at various acoustic power levels. The curve labeled P:O is the relation between drawing tension and drawing speed, under the established conditions, without the utilization of vibratory energy as an aid to drawing. Each of curves P P P and P is a curve showing such a relationship under the effect of vibratory energy activation, with increasing acoustic power, such as, for convenience of description only, 100 watts for P 200 watts for P 300 watts for P and 400 watts for P It is known, of course, that a given material (and geometry of that material) has a certain tensile strength, the exceeding of which in the course of the drawing operation, as for example by the application of a sufficient drawing tension, results in material breakage. In FIGURE 6, the value of the drawing tension limit is represented by the upper dashed line T Thus, it can be seen that, for the case of no vibratory activation and as the drawing speed is increased, the drawing tension follows the curved increasing from a point designated X until it reaches a point designated Y, where drawing tension exceeds the tension limit and the wire will break as further increase in speed is attempted. Therefore, in this particular example, the drawing is restricted to drawing speeds lying between X and Y.

It has been found that, for a given material and geometry of material to be drawn in a vibratory drawing operation, there is also a limit to the amount of acoustic power which may be advantageously applied as an auxiliary to the drawing operation, especiailly in the initial stages of drawing. In FIGURE 6, the vibratory power limit is represented by the lower dashed line P Thus, it can be seen that, operating at point Z with its associated drawing tension, drawing speed, and acoustic power level as indicated by the curve P holding drawing speed constant but continually increasing power level will result in a decrease in drawing tension as indicated by travel down the dashed line Z-Z in the direction of Z When the operating conditions reach the point Z further in crease in power will cause the operating conditions to fall below the power limit and the wire will break. Such breakage, usually occurring at the region of the drawing die or adjacent thereto (as, for example, shortly after exiting of a portion of the material from the die) may be occasioned by fatigue failure or a heat rise sufficient to cause melting or other degradation of the physical properties of the material at the localized zone.

In accordance with FIGURE 6, it will be seen that the permissible operating values of drawing tension, drawing speed, and vibratory power lie between the above mentioned two limiting boundaries; i.e., between the tension limit and the power limit. Thus, points on the tension-speed curves above the tension limit or below the power limit are hypothetical in character and are not physically realizable.

For example, assuming that it is desired to make a draw at the conditions represented by point D in FIG- URE 6, e.g., with a tension T a speed S and a vibratory power P it is apparent that breakage would result if the P value were immediately applied. Therefore, it would be necessary to begin at some lower value of power and then build up speed and power together in such a manner as to keep the operating variables between the two limits. Such an illustrative buildup of vibratory power, drawing speed, and drawing tension is exemplified by the path A-B-C-D in FIGURE 6.

It can be noted that the location of the tension limit T in FIGURE 6 is arbitrarily chosen for generalizatiin purposes and that, for certain materials it may lie below point X of FIGURE 6. Under such a circumstance, the material could not be drawn at any drawing speed or drawing tension without vibratory activation.

In accordance with the present invention, utilizing apparatus having a resonant frequency of 28 kc. with the die vibrating longitudinally of the direction of wire passage, it was found that it was impossible to reduce the diameter of soap-solution-lubricated 0.010-inch copper wire to 0.008-inch (a 36% area reduction) in a single draw without vibratory activation of the die, and with vibratory activation of the die the reduction was possible only under certain circumstances. These circumstances involved not only the drawing operation but also the threading of the die preparatory to drawing.

Thus, threading of the lead-in section length of the wire (which had been etched to a reduced diameter) through the drawing die (with insufficient force or drawing tension to draw) could not be accomplished without wire failure with either no vibratory activation or with less than about 15 watts electrical power input to the magnetostrictive transducer utilized in connection with activation of the die. Moreover, the threading could not be accomplished without wire failure if as much as 50 or 60 watts power input was abruptly applied in activating the system during threading. However, if power input during threading was at the threshold value of about 15 watts, threading of the reduced-diameter portion could be accomplished without wire failure.

Moreover, the drawing operation itself (with suflicient force or drawing tension to draw) could not be performed (because the wire broke) at initial power inputs to the transducer of 200 watts, 100 watts, and (at the other or low end of the scale) of less than about 15 watts. On the other hand, this reduction was possible if the drawing rate did not exceed 350 feet per minute and the power input was in the range between a minimum of about 17.5 watts and a maximum of 50 watts. The wire broke instantly on cessation of vibratory activation.

The tensile strength of the wire before drawing was 5.5 pounds and after drawing was 3.5 pounds, but the difference in unit strength (70,730 psi. vs. 70,510 psi.) was not significant.

In another example involving the drawing of fine wire in connection with a 38% area reduction of soap-solution-lubricated tin alloy wire Cu, 1 Ge) having an initial diameter of 0.0026-inch and a final diameter of 0.00255-inch, apparatus having a design frequency of 28 kc. was used. As the rate of drawing of the wire increased from 0 to 100 feet per minute without vibratory activation, the drawing tension changed from values in the neighborhood of 10.5 grams to 12.2 grams. As the die was activated with increasing amounts of acoustic power, the tension for a given drawing speed decreased such that at a drawing speed of 100 feet per minute with 200 watts of power, the drawing tension dropped from 12.2 grams to 4 grams, or approximately 70 percent.

At 50 ft./min. this reduction could be accomplished with 11.7 grams drawing force without vibratory activation, but 30 watts (input to transducer) enabled successful accomplishment with only 4.0 grams drawing force.

Likewise, at a drawing speed of 100 ft./min., the draw was successful without vibratory activation at 12.2 grams; with vibratory activation the following results were obtained at this speed: 30 watts-11.0 grams; 60 watts8.2 grams; 100 watts6.0 grams; 200 watts-4.0 grams.

At a drawing speed of 250 ft./min., without vibratory activation the drawing force needed was 12.0 grams; with vibratory activation: 120 watts10.5 grams; 300 watts 7.5 grams.

At a drawing speed of 500 ft./min. without vibratory activation the drawing force was 13.0 grams; with vibratory activation; 120 watts12.0 grams; 300 watts- 11.0 grams.

At a drawing speed of 1000 ft./min. without vibratory activation was 15.0 grams; with vibratory activation; 300 watts 13.8 grams.

Thus, it may be seen that varying amounts of acoustic power (expressed as electrical watts input to the transducer) may be used to obtain a given reduction depending on the desired drawing conditions. Also, care must be exercised in the amount of vibratory activation applied under a given set of conditions, so as to have sufficient power to make the reduction under said conditions but not so much power as to break the wire.

The above data for drawing of the tin alloy wire was in conformance with the following equation:

where T is the drawing tension without vibratory activation;

2 is the drawing tension with vibratory activation;

k is a constant for the equipment to be empirically determined and affected by the material of which the coupling system is made;

P is the acoustic power (expressed in electrical watts input to the transducer); and

V is the drawing speed Vibratory activation during the threading operation has been found to be necessary to avoid breakage of the material to be drawn, especially in connection withthe drawing of fine wire, when relatively large reductions are to be achieved. Vibratory activation during threading may also serve to simplify production operations, as Well as to minimize likelihood of undesirable material pickup by the unactivated die during threading, such as may be encountered with certain materials or certain reductions of a given material.

For efiicient operation, the auxiliary equipment asso ciated with drawing in accordance with the present invention should be acoustically non-compliant, so as not to introduce extraneous vibrations into the operation. Thus, the capstans and payoff and takeup spools should be essentially acoustically non-responsive, a condition attained by various known means including adjustment of mass.

It has also been found in connection with the present invention, that there is a lesser temperature increase in the material than occurs in conventional drawing, a factor of some importance for purposes of avoiding undesirable temperature-induced property changes in materials such as high carbon steel, for example. Ordinarily it would be expected that the acoustical energy would appear in the form of a temperature rise in the material, which rise would be in addition to the rise occasioned by the drawing operation per se. However, and as aforesaid, especially in connection with the drawing of fine wire, material breakage may be encountered which, whether it be occasioned by temperature rise or fatigue failure or other mechanism, may be avoided in accord ance with the present invention.

Drawing may be performed in accordance with the present invention without the use of a lubricant, or without the use of special lubricants for given materials and reductions. However, the use of a lubricant is advisable to avoid unnecessary complications and to maximize reproducibility of results particularly in commercial production.

It will be appreciated that the wattage indicated in the above examples is exemplary only, and that power input may be varied according to the present invention taking into account such factors as the operating conditions utilized, the material being drawn, and also the transducercoupling system employed.

As is well known to those skilled in the art, power output (to the work) of acoustical vibration devices is not readily ascertainable directly, and indirect determination thereof often involves the use of liquids and other aspects not suitable for ready adjustment to differing industrial applications. Moreover, permissible power input is variable according to the type of transducer utilized and the acoustical coupler geometries and materials used, as Well as such factors as the efliciencies of joints between the various members of the transducer-coupling system. For example, a magnetostrictive transducer is far more rugged and trouble-free than a ceramic transducer, but it has a lesser efficiency in converting electrical power into mechanical vibration, and steel is a more readily machinable and joinable coupler material than Monel or berylliumcopper but it has a lesser acoustical transmission efii ciency.

For those desiring to insure continued transmission efficiency of a given system (in order to obtain warning of malfunction, for example), or for those desiring to compare the relative transmission efiiciencies of a plurality of systems, means may be used such as are described in co-pending patent application Serial No. 66,642 filed November 1, 1960, for Method and Apparatus for Measurement of Acoustic Power Transmission and Impedance, by Dennison Bancroft et al.

For purposes of insuring a sufficient level of acoustical energy for purposes of the present invention, it is to be noted that provision has been made, in addition to a sufl l ficient level of electrical power input to the transducer, for acoustical amplitude transformation. Also, this acoustical amplitude transformation should preferably involve, when a magnetostrictive transducer is used, a total transformer ratio (from the driving face of the transducer to the point of energy utilization) in the range of about 3.0 to 7.5; when an electrostrictive transducer (such as one of lead zirconate titanate) is used, such transformer ratio should preferably be in the range of about 1.5 to 5. This ratio depends in part upon the material or materials of which the coupling system member or members is made.

Different transformer ratios may be used in connection with each of the transducer-coupling systems of FIG- URE 3 as, for example, to provide differing amplitudes of vibration of the various dies. Likewise differing frequencies of vibration may be provided by suitable constructionx' of the independent transducer-coupling systems.

Although the invention is shown and described herein in connection with the drawing of wire, it is to be understood that the invention is applicable generally to the drawing of elongated articles having wall structure formed at least partly about a longitudinal axis thereof. The application of the present invention to the drawing of tubing, for example, while normally contraindicated in view of both the hollow cross section presented by tubing and by the relatively much slower drawing speeds generally utilized even in commercial production, is advantageous in some instances such as those involving thick-walled tubing or higher drawing speeds.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing description as indicating the scope of the invention.

It is claimed:

1. A method of drawing and forming an elongated article of constant cross section in a die having an orifice, comprising providing an appreciable length of said article with a substantially reduced cross-sectional area, positioning in said orifice at least a portion of said reduced length of said article, pulling said article through said orifice first at low speed while applying low level vibratory energy to said die, and then increasing the vibratory energy applied to said die to a higher level and increasing drawing speed until the desired drawing speed is attained.

2. A method in accordance with claim 1 wherein the application of vibratory energy to said die is initiated while the reduced portion of said article is being pull d through the die orifice.

3. A method in accordance with claim 1 including reversing the direction of the movement of said article after it has been drawn through said die orifice, and then further drawing the thusly drawn article by passing the same through a second vibratorily activated die having a die orifice smaller than the orfice of the other die.

4. A method in accordance with claim 3 including vibrating said dies in the same direction at the same time.

5. A wire drawing apparatus comprising a die having an orifice defining a passageway, means including an acoustical transmission member for supplying vibratory energy through said transmission member to said die, said acoustical transmission member having a hole means only in a portion thereof adjacent one end, said one end of said transmission member being coupled to said die with said hole means being in line with and forming a continuation of said passageway, said vibratory energy supplying means connected to the other end of said transmission member and being positioned entirely to one side of the longitudinal axis of said passageway, means for pulling wire through said passageway, a support, and means for mounting said vibratory energy supplying means on said support in acoustical isolation from said support.

6. Apparatus in accordance with claim 5 including a second die having an orifice defining a second passageway, a second and discrete acoustical transmission member coupled to said second die, said second member being coupled to a means for supplying vibratory energy, and means for guiding wire first through the passageway of said first die and then through said second passageway, with the cross-sectional area of said second passageway being smaller than the cross-sectional area of the passageway of said first die.

7. Apparatus in accordance with claim 5 wherein said acoustic transmission member is solid for most of its length, with a portion of said transmission member adjacent said other end thereof extending at an acute angle with respect to the longitudinal axis of said passageway.

8. Apparatus in accordance with claim 5 wherein said mounting means is a sleeve coupled to said die, said sleeve being coupled to said transmission member adjacent said one end thereof, said sleeve having an end thereof which is free from attachment, and an outwardly directed flange on said sleeve intermediate its ends.

9. Apparatus in accordance with claim 8 wherein said sleeve has a length corresponding to a unit multiple of one half wavelength according to the material from which the sleeve is made and at the applied vibratory frequency and the distance between said free end and said flange being an odd unit multiple of one-quarter wavelength according to the material from which the sleeve is made and at the applied vibratory frequency.

10. Wire drawing apparatus comprising a plurality of dies each having an elongated orifice, said dies being positioned side-by-side with the longitudinal axes of neighboring orifices substantially parallel to each other; a separate means for supplying vibratory energy to each of said dies comprising: a coupler, transducer means coupled to one end of said coupler for applying vibratory energy thereto and an acoustical transmission element for each die coupled thereto and to the other end of said coupler; acoustically non-compliant means for pulling an elongated article through said dies in sequence; each die orifice being smaller in area than the die orifice preceding it in sequence; a support member; and means connecting said vibratory energy supplying means to said support member in supported relationship so as to minimize the coupling of vibratory energy to said support member.

11. Apparatus in accordance with claim 10 wherein each transmission element is an arcuate elongated rod whereby the coupler may be positioned to one side of the longitudinal axes of said orifice and with the vibratory energy supplying means being remote from said dies.

12. In a method of drawing an elongated metal article through a die orifice with the die coupled to a source of vibratory energy adapted to vibrate the die in an axial direction, and the article having a portion of reduced diameter to facilitate threading the article through the die orifice, the improvement comprising threading the reduced diameter portion through the die orifice so that the die is between the extremities of said portion, then starting initiation of transmitting vibratory energy to said die while said portion extends through the die orifice, and then increasing the intensity of the vibratory energy transmitted to the die in graduated steps after the entirety of said portion has been moved through said die orifice.

13. Wire drawing apparatus comprising a die having an orifice, an acoustical transmission member having one end portion coupled to said die for transmitting vibratory energy thereto, vibratory energy supplying means coupled to the other end portion of said member, acoustically noncompliant means for pulling an elongated article through said orifice, and control means coupled to said vibratory energy means to effect graduated increases in the power level of the vibratory energy transmitted by said member to said die whereby the level of vibratory energy transmitted to the die may be increased as the drawing 13 14 speed increases up to the drawing speed desired to efiect 2,568,303 9/51 Rosenthal 20525 the shaping of the article as it passes through the orifice. 2,638,207 5/53 Gutterrnan 20516 3,002,614 10/61 Jones 207-2 References Cited by the Examiner 5 W. Przmary Examiner.

2,158,038 5/39 Starring et a1 20s 13 MICHAEL BRINDISLExaminer- 

5. A WIRE DRAWING APPARATUS COMPRISING A DIE HAVING AN ORIFICE DEFINING A PASSAGWAY, MEANS INCLUDING AN ACOUSTICAL TRANSMISSION MEMBER FOR SUPPLYING VIBRATORY ENERGY THROUGH SAID TRANSMISSION MEMBER TO SAID DIE, SAID ACOUSTICAL TRANSMISSION MEMBER HAVING A HOLE MEANS ONLY IN A PORTION THEREOF ADJACENT ONE END, SAID ONE END OF SAID TRANSMISSION MEMBER BEING COUPLED TO SAID DIE WITH SAID HOLE BEING IN LINE WITH AND FORMING A CONTINUATION OF SAID PASSAGEWAY, SAID VIBRATORY ENERGY SUPPLYING MEANS CONNECTED TO THE OTHER END OF SAID TRANSMISSION MEMBER AND BEING POSITIONED ENTIRELY TO ONE SIDE OF THE LONGITUDINAL AXIS OF SAID PASSAGEWAY, MEANS FOR PULLING WIRE THROUGH SAID PASSAGEWAY, A SUPPORT, AND MEANS FOR MOUNTING SAID VIBRATORY ENERGY SUPPLYING MEANS ON SAID SUPPORT IN ACOUSTICAL ISOLATION FROM SAID SUPPORT. 